Abstract
Although the Kearns-Shy syndrome (KSS) is now recognized as one of disorders of mitochondrial dysfunction characterized by external ophthalmoplegia, retinal pigmentary degeneration, and heart block. cas having full-blown symptoms are rare. We recently examined four children with KSS. One case had a family history of KSS. Ptosis, external ophthalmoplegia, and neurosensory hearing loss were observed in all cases. So-called “atypical pigmentary degeneration of the retina” was demonstrated in three. Failure of cardiac conduction was demonstrated in two patients ; in one an epicardiac ventricular demand pacemaker was in-serted. Short stature and mild muscular weakness were seen in all cases. Cerebellar signs such as tremor were detected in two cases. Endocrine disorders were seen in two cases ; one presented growth hormone deficiency, and the other insulin dependent diabetes mellitus. Elevated CSF protein levels were demonstrated in all cases, but serum lactate and pyruvate levels were normal except for one case. EEGs were abnormal in three patients, all showing dysrhythmic basic rhythm. Intelligence was low normal in all cases. Computed tomographic scans demonstrated diffuse low density changes in the white matter of one case. In three cases “ragged red fibers” were shown in muscle biopsy specimens, and the electron microscopic examination showed some stractural abnormalities of mitochondria in three cases. Large mitochondria with proliferation of cristae were prominent, but paracrystalline arrangement of cristae was scarsely observed. The appearance of characteristic features of KSS might depend upon the clinical stage of this disorder, but different clinical and biochemical features might indicate heterogeneity of this syndrome.
